Generally, exemplary structures used by connecting pipes are city water and sewage pipes, gas pipes, street lamp pipes, sign boards, indication plates, etc. Some of electric sign boards, advertisement boards, etc. have the same pipe connection structure. Most of the systems for connecting such structures are made by welding or have a screw structure, which disadvantageously needs in turn a lot of time and labor for connection and disconnection.
Furthermore, most of pipe joints are made by welding or screwing when connecting the pipes. In case of a large pipe, a rubber ring is used to cover the pipe connection, then overly it with a ring-shaped metal to couple it with a bolt. Such a connection method, however, is time and labor consuming work which is annoying in disassembling the structure because the work should be done in a reverse order.
In particular, when installing, maintaining and disassembling a street lamp or a sign board, the work must be done rapidly, and a rapid and robust coupling system is also required when equipping or repairing a large city water or sewage pipe or a gas pipe in an emergency.
In order to meet such a need, there are disclosed inventions or designs of a structure for exerting wedge action on the outer diameter of a pipe for fixing the pipe: Japan Patent Application No. 2001-21076, Korea Utility Model Registration No. 20-0325868 and published Korea Patent Application No. 10-2004-0077623, wherein the structure functions the same as the pipe fixing system according to the invention.
The structure, however, disclosed in the aforementioned Japan Patent No. 2001-21076 has a complicated structure such as a gland, two flanges, a lock ring, an encore, etc. which need a lot of production cost and do not have a good appearance, and may also be damaged during storage, installation and transportation because the parts of bolts and flanges excessively protrude to the outside, unlike the structure according to the invention.
Also, in the utility model disclosed in Korea Utility Model Registration No. 20-0325868, it is very hard to fix a pipe 10 in a secure way because the inner side of the fixing chip 24 contacting the outside of the pipe 10 is produced smooth, as shown in FIG. 1. Since the inlet 23 is integrated with the body 20, the entry (23) of the body (20) may be broken or the pipe (10) may be damaged when tension or torsion is exerted on the pipe (10) while the pipe (10) rests on the guide wall (29) and the stop (21) and is coupled by means of a bolt.
In the invention disclosed in the published Korea Patent No. 10-2004-0077623, a pipe id fixed by means of elasticity of a plate-type spring, but the spring cannot have elasticity enough to fix a pipe whose diameter is more than 100 mm in a secure way.